Sociocultural determination of linguistic complexity

Abstract

Languages evolve, adapting to pressures arising from their learning and use. As these pressures may be different in different sociocultural environments, non-linguistic factors relating to the group structure of the people who speak a language may influence the features of the language itself. Identifying such factors, and the mechanisms by which they operate, would account for some of the diversity seen in the complexity of different languages. This thesis considers two key hypotheses which connect group structure to complex language features and evaluates them experimentally. Firstly, languages spoken by greater numbers of people are thought to be less morphologically complex than those employed by smaller groups. I assess two mechanisms by which group size could have such an effect: different degrees of variability in the linguistic input learners receive, and the effects of adult learning. Four experiments conclude that there is no evidence for different degrees of speaker input variability having any effect on the cross-generational transmission of complex morphology, and so no evidence for it being an explanation for the effect of population size on linguistic complexity. Three more experiments conclude that adult learning is a more likely mechanism, but that linking morphological simplification at the level of the individual to group-level characteristics of a language cannot be simply explained. Idiosyncratic simplifications of adult learners, when mixed with input from native speakers, may result in the linguistic input for subsequent learners being itself complex and variable, preventing simplified features from becoming more widespread. Native speaker accommodation, however, may be a key linking mechanism. Speakers of a more complex variant of a language simplify their language to facilitate communication with speakers of a simpler language. In doing so, they may increase the frequency of particular simplifications in the input of following learners. Secondly, esoteric communication | that carried out by smaller groups in which large amounts of information is shared and in which adult learning is absent | may provide the circumstances necessary for the generation and maintenance of more complex features. I assess this in four experiments. Without a learnability pressure, esoteric communication illustrates how complexity can be maintained, but there is generally no evidence of how smaller groups or those with greater amounts of shared information would develop comparatively more complex features. Any observable differences in the complexity of the languages of different types of groups is eliminated through repeated interaction between group members. There is, however, some indication that the languages used by larger groups may be more transparent, and so easier for adult learners to understand.